-- Domain schema for rusty_petroleum (v1: fuel domain)
-- Optimized for MariaDB / InnoDB
--
-- Scope: the six tables below plus invoice_items cover the v1 "in
-- development" features (epsilon ingest, invoices). Auth (users,
-- sessions, roles) and the tsdrms / subfranchise / voucher / car
-- registry domains arrive as later embedded migrations, per the
-- decisions recorded 2026-09. In the application this file becomes
-- the first embedded migration, applied by `db setup` behind the
-- schema_migrations table (see readme.md); the DROP block below is
-- the reset path (`db reset` drops the whole database).
--
-- Design decisions (agreed with maintainer, 2026-09):
--  - cards.pin: NULL-able; created without pin on import. Stored
--    cleartext on purpose: customers retrieve it in the portal, and
--    the cards are only used on-site at the station, so the risk is
--    accepted.
--  - transactions is a SLIM PROJECTION (9 of 16 source fields):
--    QualityName, Card type, Station, Terminal, Pump, Card report
--    group number and Control number are dropped. The files table (full
--    byte content) is the canonical archive; the ledger keeps only what
--    application features query.
--  - Customer business key is the register customer number, stored as
--    a STRING in both customers.external_id and
--    transactions.customer_number (arrives as quoted text in the CSV;
--    always 4 digits today, but bookkeeping/Fortnox features cannot
--    guarantee numeric-only). NULL = retail/unknown (replaces the 0
--    sentinel).
--  - Money is DECIMAL(10,2) SEK everywhere (VAT-inclusive as
--    delivered); the BIGINT-cents representation is dropped.
--  - Invoice status values are exactly cli.md's: draft / sent. Card
--    statuses: active / suspended / cancelled. (cli.md is the spec.)
--  - Invoices carry full source traceability: batch_id or date range,
--    per-transaction line items, and credit invoices reference the
--    invoice they correct.

SET FOREIGN_KEY_CHECKS = 0;
DROP TABLE IF EXISTS invoice_items;
DROP TABLE IF EXISTS invoices;
DROP TABLE IF EXISTS transactions;
DROP TABLE IF EXISTS cards;
DROP TABLE IF EXISTS batches;
DROP TABLE IF EXISTS customers;
DROP TABLE IF EXISTS files;
SET FOREIGN_KEY_CHECKS = 1;

-- 1. Imported source files
-- filename is the natural key (readme.md: filenames carry metadata and
-- make re-ingestion idempotent); checksum catches byte-identical
-- re-imports. content holds the full byte-faithful source so
-- `file export --format raw` works and the DB is the archive of
-- record. One file may span many batches (cumulative exports);
-- batch_number is set only for single-batch files.
CREATE TABLE files (
    id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    filename VARCHAR(255) NOT NULL,
    format VARCHAR(20) NOT NULL,        -- 'epsilon-tsv' (v1); tsdrms / subfranchise later
    checksum VARCHAR(64) NOT NULL,      -- SHA-256, dedup of byte-identical re-imports
    content LONGTEXT NOT NULL,          -- raw source, byte-faithful
    row_count INT UNSIGNED NOT NULL,    -- data rows parsed from the file
    batch_number INT UNSIGNED,          -- single-batch files only; NULL for cumulative
    imported_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE INDEX idx_filename (filename),
    UNIQUE INDEX idx_checksum (checksum)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- 2. Customers (contract fuel customers)
-- Identity is the register customer number (business key). VARCHAR:
-- the number arrives as quoted text, is 4 digits in all samples, and
-- must not be assumed numeric-only when bookkeeping features arrive.
CREATE TABLE customers (
    id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    external_id VARCHAR(100) NOT NULL,  -- register customer number, as delivered
    name VARCHAR(255) NOT NULL,
    address TEXT,
    email VARCHAR(255),
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE INDEX idx_external_id (external_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- 3. Batches (derived entity: one per register batch; created and
-- maintained by file import, recomputed by `batch update`).
-- The batch number from the filename/rows is the business key.
-- Cached aggregates mirror transactions; no FK to files (the relation
-- is derivable via transactions.imported_file_id + batch_number).
CREATE TABLE batches (
    id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    batch_number INT UNSIGNED NOT NULL, -- business key, from filename/rows
    start_date DATE NOT NULL,           -- min transaction date in the batch
    end_date DATE NOT NULL,             -- max transaction date in the batch
    total_amount DECIMAL(10,2) NOT NULL,-- cached sum of amounts (SEK, VAT-incl.)
    transaction_count INT UNSIGNED NOT NULL, -- cached row count
    status VARCHAR(20) NOT NULL,        -- open / closed / invoiced
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE INDEX idx_batch_number (batch_number)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- 4. Cards (contract fuel cards only: epsilon rows with a customer
-- number; retail rows carry no card). One card per card number; the
-- same number may recur across batches.
CREATE TABLE cards (
    id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    customer_id INT UNSIGNED NOT NULL,
    card_number VARCHAR(50) NOT NULL,   -- as delivered (unmasked for contract cards)
    pin VARCHAR(20),                    -- NULL until known; cleartext by decision (on-site cards)
    status VARCHAR(20) NOT NULL,        -- active / suspended / cancelled
    description TEXT,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE INDEX idx_card_number (card_number),
    INDEX idx_customer_id (customer_id),
    FOREIGN KEY (customer_id) REFERENCES customers(id) ON DELETE RESTRICT
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- 5. Transactions (the immutable ledger)
-- Created only by file import; no create/update/delete commands.
-- Slim projection of the 16 source fields (decision above); raw
-- values as delivered, so NO foreign keys to cards/customers --
-- customer_number/card_number are raw strings, joinable by equality
-- with customers.external_id / cards.card_number. The only FK is
-- provenance: which file the row came from.
CREATE TABLE transactions (
    id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    transaction_date DATETIME NOT NULL, -- parsed from M/d/yyyy h:mm:ss AM/PM
    amount DECIMAL(10,2) NOT NULL,      -- SEK, VAT-inclusive; = volume x price
    volume DECIMAL(10,2) NOT NULL,      -- liters
    price DECIMAL(10,2) NOT NULL,       -- SEK/liter
    quality INT NOT NULL,               -- 1001 = unleaded ("95 Oktan"), 4 = diesel, 0 = zero-value
    card_number VARCHAR(50) NOT NULL,   -- as delivered (masked for consumer cards)
    customer_number VARCHAR(100),       -- as delivered; NULL = retail/unknown
    receipt VARCHAR(20) NOT NULL,       -- zero-padded at 6 digits in all samples; widened deliberately
    batch_number INT UNSIGNED NOT NULL, -- matches the filename; always present
    imported_file_id INT UNSIGNED NOT NULL,
    UNIQUE INDEX idx_dedup (transaction_date, receipt), -- re-ingestion dedup; verified unique in the 138k-row sample
    INDEX idx_batch_number (batch_number),
    INDEX idx_customer_number (customer_number),
    INDEX idx_card_number (card_number),
    FOREIGN KEY (imported_file_id) REFERENCES files(id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
-- (The old standalone idx_transaction_date was dropped: the unique
-- (transaction_date, receipt) prefix already serves date-range scans.)

-- 6. Invoices (outgoing fuel invoices only; one buyer per invoice)
-- Created from a batch OR a date range, per customer ("all" fans out).
-- full traceability: batch_id and/or the effective period, plus one
-- line item per source transaction; credit invoices reference the
-- sent invoice they correct. Amounts DECIMAL SEK, VAT-inclusive;
-- the 25% base/VAT split is computed at creation.
CREATE TABLE invoices (
    id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    invoice_number VARCHAR(100) NOT NULL, -- assigned by the app at creation
    customer_id INT UNSIGNED NOT NULL,
    batch_id INT UNSIGNED,                -- set for --batch creation; NULL for date-range
    from_date DATE NOT NULL,              -- effective period start (batch dates or --from)
    to_date DATE NOT NULL,                -- effective period end (batch dates or --to)
    issue_date DATE NOT NULL,
    due_date DATE NOT NULL,
    total_amount DECIMAL(10,2) NOT NULL,  -- VAT-inclusive; negative for credit invoices
    status VARCHAR(20) NOT NULL,          -- draft / sent (v1)
    original_invoice_id INT UNSIGNED,     -- set on credit invoices; NULL otherwise
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE INDEX idx_invoice_number (invoice_number),
    INDEX idx_customer_id (customer_id),
    INDEX idx_batch_id (batch_id),
    INDEX idx_issue_date (issue_date),
    INDEX idx_original_invoice_id (original_invoice_id),
    FOREIGN KEY (customer_id) REFERENCES customers(id) ON DELETE RESTRICT,
    FOREIGN KEY (batch_id) REFERENCES batches(id) ON DELETE RESTRICT,
    FOREIGN KEY (original_invoice_id) REFERENCES invoices(id) ON DELETE RESTRICT
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- 7. Invoice line items (one per source transaction)
-- description is derived at creation (quality code -> name lookup,
-- volume/price text); amount is the transaction amount, VAT-incl.
CREATE TABLE invoice_items (
    id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    invoice_id INT UNSIGNED NOT NULL,
    source_transaction_id BIGINT UNSIGNED NOT NULL,
    description VARCHAR(255) NOT NULL,
    amount DECIMAL(10,2) NOT NULL,
    INDEX idx_invoice_id (invoice_id),
    INDEX idx_source_transaction_id (source_transaction_id),
    FOREIGN KEY (invoice_id) REFERENCES invoices(id) ON DELETE CASCADE,
    FOREIGN KEY (source_transaction_id) REFERENCES transactions(id) ON DELETE RESTRICT
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;